Choice between post-reinforcer delays in pigeons: Effects of stimulus continuity and response requirement

This study examined the effects of stimulus continuity and response requirements on pigeon choices between post-reinforcer delays (from 2 s to 8 s) using concurrent-chains schedules with FR 1 schedules arranged for the choice phase. In Experiment 1, using seven pigeons, the effect of stimulus continuity, the presentation of the same stimulus (background color of the computer screen) during the post-reinforcer delay period as in the pre-reinforcer delay period, was examined. In Experiment 2, the effect of stimulus continuity was examined under the conditions where a response was required (FR 1) to initiate the post-reinforcer delay using eight pigeons. The experimental results indicated that when the same stimulus as in the pre-reinforcer delay was presented continuously during the post-reinforcer delay and a response was required to start the post-reinforcer delay, the subjects showed relatively high sensitivity to differences between post-reinforcer delays. The implications of the results are discussed from a new perspective for the analysis of self-control choices.